Lone, I find that there is so much variation within the hawthorns that a meaningful answer is difficult. In other words, I think there are some hawthorns that are sufficiently subject to the various leaf blights and so on as to make them unfit for a key spot in the landscape, but that there are others with no such issues. Additionally, Crataegus is one of those "promiscuous" genera for which much self-hybridization goes on, making both ID and predictions about the behavior of any one plant difficult, for me anyway. Sorry for the non-answer!

Hawthorns are insect and disease magnets. However, the insects and diseases they attract are mostly of a cosmetic nature, and rarely cause any permanent damage. It is common to see species and cultivars of hawthorn bare of foliage by mid to late summer. Great for native pollinators and larval food for moths and butterflies, and winter forage for birds. They are very tough, easy to grow trees, but they may be better suited to more naturalistic settings, rather than a highly manicured landscape. It really depends on the look you want, and if you are willing to constantly spray to keep the trees looking pristine. In that respect they would be very much like fruit trees. And of course, SOME are very thorny. As for Washington, I personally like the tree and have one, as well as several volunteers of unknown species. The genus Crataegus is one of, if not THE most difficult to ID.

Some, including the species laviegata (Paul's' Scarlet and Crimson Cloud), are prone to a fungal leaf spot that, if severe enough, can cause early defoliation. And they are all susceptible to cedar-apple rust if a host species is present.

They are for a farmyard where suburban ornamentals will look a little too fussy...the Hawthorn knarled look is better. I planted a wild bareroot Hawthorn last fall beside the Crimson. The leaves were covered in rust immediately this spring, so I figure it came diseased from the nursery. I yanked it out of the ground and bagged it. I have a few fruit trees that just went in so I could spray the Hawthorns as part of their regimen. I'd rather a cultivar than a more unknown wild chancer again. A local nursery has a Washington I'll ask them to save for fall planting.